On 2/10/2011 12:47 PM Cheesehead spake thus:
I'm not absolutely certain about the Geronar formula. It is reported
to be a Tessar.
That said, the rear should be a single piece of glass. But it is not.
If it is a cemented piece, then it is not a true Tessar and the
fogging may be in the cement.
That would be bad.
I've not found the formula out there to describe the lens.
In the mean time I've been searching for a replacement rear cell.

It's not clear you've tried to remove and clean the rear cell; have you?
If not, you should. What've you got to lose? If in fact the cement is
clouded (which I think is probably unlikely), you've got to replace the
thing anyhow (or have it recemented), so why not just pull it out and
clean it? It ain't rocket surgery, you know.

--
Comment on quaint Usenet customs, from Usenet:

To me, the *plonk...* reminds me of the old man at the public hearing
who stands to make his point, then removes his hearing aid as a sign
that he is not going to hear any rebuttals.